Coalesce some allocations (#3747)

* View: Coalesce view model allocations
* SceneManager: Coalesce AppScene allocations
* BufferStream: Coalesce Buffer allocations
* ProtocolDict: Coalesce dict allocations
* DigitalSignal: Coalesce buffer allocations

Co-authored-by: あく <alleteam@gmail.com>

lib/digital_signal/digital_signal_i.h

@@ -18,6 +18,6 @@ struct DigitalSignal {
     bool start_level; /**< The level to begin the signal with. */
     uint32_t size; /**< Current period count contained in the instance. */
     uint32_t max_size; /**< Maximum period count this instance can hold. */
-    uint32_t* data; /**< Pointer to the array of time periods. */
     int32_t remainder; /**< Remainder left after converting all periods into timer ticks. */
+    uint32_t data[]; /**< The array of time periods. */
 };